A major obstacle to high-level performance on a wide variety of activities is interference by external factors, in the form of distraction and multitaskng. The negative impact of external interference on performance has been shown to worsen with age, and is a prominent factor in cognitive aging. Remarkably, it has been shown that adults of all ages can learn to resolve external interference with practice, largely eliminating performance costs. The basic science goals of the proposed research project are to explore the neural basis of external interference, how we learn to resolve interference with practice and how these mechanisms change with age. From a translational perspective, parallel goals are to assess the transfer of learning to benefit other cognitive abilities and the sustainability of learned skills ver time. To accomplish these goals, younger and older adults will engage in cognitive training regimens, which were specifically developed to train distraction and multitasking abilities. Neural mechanisms of interference effects and learning will be assessed before and after training using simultaneous electroencephalography (EEG) and functional MRI (fMRI) recordings while participants engage in an experimental version of the training tasks. Temporal and spatial measures of cortical function, with an emphasis on network connectivity, will be evaluated. Direct comparisons between age groups will offer a basis to understand alterations in these mechanisms that occur with normal aging. An extensive battery of cognitive tasks and real-life activity measures will also be administered pre- and post-training to evaluate if learning to resolve interference improves other abilities. Participants will be re-tested six months after training on the experimental tasks to assess sustainability of learning. In addition to advancing the limited work in this important area, we anticipate that the unique methodological approach and experimental design of this project will have a major impact on the field. This knowledge will be used to guide the targeted development of rehabilitation programs directed at the broad range of cognitive abilities and clinical populations that are susceptible to negative effects of interference.